Why doesn’t Quicksilver tell Magneto about their connection?

This is the best example of how not to prolong a story. In Days of Future Past, it is hinted that Quicksilver is Magneto‘s son. In the promotional interviews, Evan Peters says that Quicksilver is aware that Magneto is his father, and he’ll be searching for him. For the arc to be completed, and for Magneto to have a better reason for switching sides, Quicksilver should have told him that he’s his son.
It doesn’t happen. And I don’t know why. Yes, it would be a bit cheesy, and all those who are familiar with the characters would see it coming a mile away.
Instead of doing that, the powers that be decided that Quicksilver’s story needs to be prolonged. Why? I guess we’ll find out.
And speaking of Quicksilver…
